The invention relates to an apparatus for the application of rectilinear relief cuts to previously scored glass sheets, especially those having a curvilinear external contour, such as motor vehicle windowpanes or the like.
In the large-scale production of glass sheets, especially motor vehicle windowpanes, the cutting out or the preliminary scoring of the windowpane shape from suitably dimensioned, usually rectangular glass blanks is performed with automatic cutting machines in which, after the insertion of the blanks, a cutting wheel mounted in a cutting head is lowered onto the blank and is guided on a suitably shaped pattern. At the end of the cutting process, the cutting wheel, which has returned to its starting position, is raised again. The scored blank is carried from the automatic cutting machine by means of a roller conveyor or other transporting means to a breaking station in which the marginal waste portion is then broken off.
If the windowpane shapes are suitably simple, the breaking off of the marginal waste can be performed automatically by machine. Certain windowpane shapes, however, especially windshields, back windows and specially shaped side windows of motor vehicles, when they have curvilinear or arcuate edges, cannot be broken out in this manner. Instead, one or more relief cuts must be made at suitable places on the marginal waste portion to prevent damaging the outlined windowpane.
Hitherto the relief cuts have been made by an operator using a manual glass cutter, after which the margin is then broken away by hand. The making of the relief cuts requires the special attention of an experienced operator, because the start of the relief cut must be located precisely at the outer contour of the windowpane which has been scored by the automatic cutting machines. If the cut is made too far from the machine-scored line, projecting sharp points often develop when the marginal waste is broken away, which then have to be ground off. But if the cut begins inside of the machine-scored windowpane contour, the windowpane becomes useless, because this scratch is the starting point for later cracking of the glass during hardening or under bending stresses after installation in the motor vehicle.
The fact that an experienced operator is required in order to make the relief cuts by hand results in relatively high production costs. Also, the quality of the windowpanes produced will vary according to the care which the workman actually exercises.